Apparatus for controlling the angle of a swash plate of a hydraulic pump

ABSTRACT

The present disclosure relates to an apparatus for controlling the angle of a swash plate of a hydraulic pump, and more particularly, to an apparatus for controlling the angle of a swash plate of a hydraulic pump in order to fix the swash plate at a desired angle by using an electric motor and an electromagnet. The apparatus for controlling the angle of a swash plate of a hydraulic pump includes a swash plate and a swash plate shaft coupled to the swash plate to be rotatable, and the apparatus further includes: an electric motor which directly connects the swash plate shaft or transmits a rotating force through a link connected to the swash plate shaft to pivot the swash plate; and an electromagnet which generates a magnetic force so that the swash plate moving according to the operation of the electric motor is fixed at a target angle.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2011-0010608, filed on Feb. 7, 2011, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.

BACKGROUND

1. Field

The present disclosure relates to an apparatus for controlling the angle of a swash plate of a hydraulic pump, and more particularly, to an apparatus for controlling the angle of a swash plate of a hydraulic pump in order to fix the swash plate at a desired angle by using an electric motor and an electromagnet.

2. Description of the Related Art

A tractor or working vehicle may do plowing or flattening or other agricultural works using the power of an engine, and a loader or mower may be attached to the tractor to perform various kinds of works. The tractor or working vehicle may be operated at various speeds by means of an engine and a transmission, and the transmission may employ a manual transmission, an automatic transmission or a continuously variable transmission, similar to a vehicle.

FIGS. 1 to 3 are schematic diagrams for illustrating how to control the angle of a swash plate of a general hydro static transmission (HST), and FIG. 4 is a graph showing an actual change of the angle of a swash when the angle of a swash is controlled using the configuration of FIG. 3.

Referring to FIGS. 1 to 3, the HST includes an axial piston-type hydraulic pump 12 and a hydraulic motor 13. If an engine 11 operates the hydraulic pump 12, a hydraulic pressure is transmitted to the hydraulic motor 13 through a channel connected to the hydraulic pump 12. Subsequently, the hydraulic motor 13 generates a rotating force by using the hydraulic pressure transmitted from the hydraulic pump 12 to rotate a wheel 18 via a reduction gear 17.

If the angle of the pivotable swash plate 14 is changed, an amount of operating oil of the hydraulic pump 12 may increase or decrease to change a flow rate. Accordingly, a rotating direction and rotating speed of the output shaft of the hydraulic motor 13 may be adjusted.

In FIG. 1, a swash plate 14 of the hydraulic pump 12 is directly connected to a driver pedal 15, and the driver may drive a vehicle to a desired rotating direction or rotating speed by manipulating the pedal 15. This configuration may be realized with a low cost. However, if a load is applied to the wheel 18, the pressure of the hydraulic pump 12 and the hydraulic motor 13 increases, and a great torque is applied to the swash plate 14. Therefore, a driver should use a great force to manipulate the pedal 15, which results in inconvenient manipulation.

In FIG. 2, a hydraulic valve 25 connected to a swash plate 24 of the hydraulic pump 12 is added to control the operation of the swash plate 24 by a hydraulic pressure, and the angle of the swash 24 may be manipulated with a consistent force regardless of the load from the wheel 18 of the vehicle. In addition, an electronic hydraulic valve 25 may be installed to perform automatic transmission suitable for conditions, but this configuration is expensive.

In FIG. 3, an electric motor 35 connected to a swash plate 34 of the hydraulic pump 12 is added to control the operation of the swash plate 34 by a rotating force of the electric motor 35. This configuration is cheap and may perform transmission regardless of the load. However, this configuration has a problem in that the electric motor 35 may not be easily controlled.

In other words, as shown in FIG. 4, under the condition that a load is generated at the wheel 18, as the pressure of the hydraulic pump 12 and the hydraulic motor 13 increases, the swash plate 34 generates a force to return to a neutral location. Therefore, the electric motor 35 applies a rotating force to the swash plate 34 by feed-back control so that the swash plate 34 departing from the control region moves to a target location. However, in this process, the angle of the swash plate 34 fluctuates within the control region, which causes the operating vehicle to fluctuate, makes the driver feel unpleasant and deteriorates the durability of the electric motor 35.

In order to solve this problem, it is possible to increase the capacity of the electric motor 35 or add a worm gear or a screw to the electric motor 35 so that the power is not released. However, these solutions have problems in that the size of the motor increases or the cost increases.

SUMMARY

The present disclosure is directed to providing an apparatus for controlling the angle of a swash plate of a hydraulic pump which may fix the swash plate at a desired angle by using an electric motor and an electromagnet.

In one aspect, there is provided an apparatus for controlling the angle of a swash plate of a hydraulic pump, which includes a swash plate and a swash plate shaft coupled to the swash plate to be rotatable, the apparatus including: an electric motor which directly connects the swash plate shaft or transmits a rotating force through a link connected to the swash plate shaft to pivot the swash plate; and an electromagnet which generates a magnetic force so that the swash plate moving according to the operation of the electric motor is fixed at a target angle.

The electromagnet may be mounted in the electric motor to apply a magnetic force to a rotary shaft of the electric motor so that the electric motor stops rotation.

The electromagnet may be disposed adjacent to the link which connects the swash plate shaft to the electric motor and may apply a magnetic force to the link so that the link is fixed.

The electromagnet may be switched off while the electric motor is operating, and the electromagnet may be switched on if the swash plate reaches a target angle so that the swash plate is fixed due to the magnetic force.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the disclosed exemplary embodiments will be more apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIGS. 1 to 3 are schematic diagrams for illustrating the angle control of a swash plate of a general hydro static transmission (HST);

FIG. 4 is a graph showing an actual change of the angle of a swash plate when the angle of the swash is controlled using the configuration of FIG. 3;

FIGS. 5 and 6 are schematic views showing an apparatus for controlling the angle of a swash plate of a hydraulic pump according to an exemplary embodiment of the present disclosure; and

FIGS. 7 and 8 are schematic view showing an apparatus for controlling the angle of a swash plate of a hydraulic pump according to another exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Exemplary embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth therein. Rather, these exemplary embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of the terms a, an, etc. does not denote a limitation of quantity, but rather denotes the presence of at least one of the referenced item. The use of the terms “first”, “second”, and the like does not imply any particular order, but they are included to identify individual elements. Moreover, the use of the terms first, second, etc. does not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. It will be further understood that the terms “comprises” and/or “comprising”, or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In the drawings, like reference numerals denote like elements. The shape, size and regions, and the like, of the drawing may be exaggerated for clarity.

Hereinafter, an apparatus for controlling the angle of a swash plate of a hydraulic pump according to exemplary embodiments of the present disclosure will be described in detail.

FIGS. 5 and 6 are schematic views showing an apparatus for controlling the angle of a swash plate of a hydraulic pump according to an exemplary embodiment of the present disclosure.

Referring to FIGS. 5 and 6, an apparatus for controlling the angle of a swash plate according to the exemplary embodiment includes an electric motor 150 and an electromagnet 160. The power transmitted from an engine 11 progresses via hydro static transmission (HST) 120 and a transmission 16 to a reduction gear 17. The engine 11, the HST 120 and the reduction gear 17 are identical or similar to existing ones and therefore not described in detail here.

The electric motor 150 is directly connected to a swash plate shaft 142 of a hydraulic pump 12 or transmits a rotating force through links 122 and 124 connected to the swash plate shaft 142 to pivot a swash plate 140. Though the electric motor 150 is connected to the swash plate shaft 142 by the links 122 and 124 in FIG. 6, the electric motor 150 may be directly connected to the swash plate shaft 142. The swash plate shaft 142 is coupled to the swash plate 140 to rotate integrally with the swash plate 140.

The electromagnet 160 generates a magnetic force so that the swash plate 140 which moves according to the operation of the electric motor 150 is fixed at a target location. In the exemplary embodiment, the electromagnet 160 is mounted in the electric motor 150 to apply a magnetic force to the rotary shaft of the electric motor 150 so that the electric motor 150 stops rotation.

The electromagnet 160 is magnetized to generate a magnetic force if electric current flows thereon. If the electromagnet 160 is operated while the electric motor 150 operates, the magnetic force may cause malfunction of the electric motor 150. Therefore, the electromagnet 160 is switched off not to operate while the electric motor 150 is operating, and if the swash plate 140 reaches a target angle by the operation of the electric motor 150, the electromagnet 160 is switched on to fix the rotary shaft of the electric motor 150 by a magnetic force.

In other words, once the swash plate 140 reaches a target angle, the operation of the electric motor 150 is stopped, and the electromagnet 160 is operated so that the swash plate 140 maintains a consistent angle. Accordingly, when a load is applied, it is not needed to periodically operate the electric motor 150 so as to maintain the angle of the swash plate 140, and the fluctuation of the vehicle does not occur by the feed-back control of the electric motor 150.

FIGS. 7 and 8 are schematic view showing an apparatus for controlling the angle of a swash plate of a hydraulic pump according to another exemplary embodiment of the present disclosure.

Referring to FIGS. 7 and 8, the apparatus for controlling the angle of a swash plate according to the exemplary embodiment includes an electric motor 250 and an electromagnet 260 disposed adjacent to links 222 and 224.

The electric motor 250 transmits a rotating force through the links 222 and 224 connected to a swash plate shaft 242 to pivot a swash plate 240. Since a control device of this embodiment is configured using the electric motor 250, it is possible to perform transmission of a vehicle at a low cost regardless of the load applied to a wheel 18.

The electromagnet 260 is disposed adjacent to the links 222 and 224 which connects the swash plate shaft 242 to the electric motor 250 and applies a magnetic force to the links 222 and 224 to fix the links 222 and 224. As the links 222 and 224 are fixed by the magnetic force of the electromagnet 260, the rotary shaft of the electric motor 250 stops rotation.

As described above, the electromagnet 260 is switched off not to operate while the electric motor 250 is operating, and if the swash plate 240 reaches a target angle by the operation of the electric motor 250, the electromagnet 260 is switched on to operate to flow electric current and thus generate a magnetic force so that the rotary shaft of the electric motor 250 is fixed.

The size and capacity of the electromagnet 160 and 260 may be changed in various ways in consideration of a desired intensity of a magnetic force according to the material of the links and the rotary shaft of the electric motor 150 and 250.

The apparatus for controlling the angle of a swash plate of a hydraulic pump according to the present disclosure allows the swash plate to be fixed at a desired angle by using an electric motor and an electromagnet.

In addition, the apparatus for controlling the angle of a swash plate of a hydraulic pump according to the present disclosure can reduce the frequent operations of the electric motor by adding an electromagnet, which can improve the durability of the electric motor.

Further, the apparatus for controlling the angle of a swash plate of a hydraulic pump according to the present disclosure has a simple design and can be added to and used for an existing transmission at a low cost.

While the exemplary embodiments have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made thereto without departing from the spirit and scope of the present disclosure as defined by the appended claims.

In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular exemplary embodiments disclosed as the best mode contemplated for carrying out the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the appended claims. 

1. An apparatus for controlling the angle of a swash plate of a hydraulic pump, which includes a swash plate and a swash plate shaft coupled to the swash plate to be rotatable, the apparatus comprising: an electric motor which directly connects the swash plate shaft or transmits a rotating force through a link connected to the swash plate shaft to pivot the swash plate; and an electromagnet which generates a magnetic force so that the swash plate moving according to the operation of the electric motor is fixed at a target angle.
 2. The apparatus for controlling the angle of a swash plate of a hydraulic pump according to claim 1, wherein the electromagnet is mounted in the electric motor to apply a magnetic force to a rotary shaft of the electric motor so that the electric motor stops rotation.
 3. The apparatus for controlling the angle of a swash plate of a hydraulic pump according to claim 1, wherein the electromagnet is disposed adjacent to the link which connects the swash plate shaft to the electric motor and applies a magnetic force to the link so that the link is fixed.
 4. The apparatus for controlling the angle of a swash plate of a hydraulic pump according to claim 1, wherein the electromagnet is switched off while the electric motor is operating, and the electromagnet is switched on if the swash plate reaches a target angle so that the swash plate is fixed due to the magnetic force. 